<script setup lang='ts'>
import { ref, watch } from 'vue';

 const count = ref(0)
 watch(count, (newValue, oldValue) => {
   console.log(newValue, oldValue)
 })
</script>
       
<template>
    <h1>Watch最简单用法</h1>
    <button @click="count--">-</button>   
    <span>{{ count  }}</span>
    <button @click="count++">+</button>   
</template>
       
<style scoped>
       
</style>